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Battery Charge Loss: Overnight

Battery Charge Loss: Overnight

Submitted by blakehajek on 17. Februar 2013

Does anyone else notice that their Model S loses charge over night? I went to Tesla Menlo Park yesterday and told them this, but hey said that the charge loss would replenish itself once I started driving. They explained that this was due to the cold temperature at night, which caused a misreading in the morning. My takeaway from the conversation was that the battery under cold temperatures acts similar to that of a car driving up or down a hill: the "gas tank" misreads the level of fuel in the tank.

So I took my car home last, checked the mileage, went to breakfast this morning, and not only did the car register 30% less charge but it did not replenish. It also lost 2 miles of charge for a 1 mile trip. I drove normally. I checked my phone and it had been logged in to when I checked the mileage last night before I went to sleep: 61 miles
It changed to 38. It was at 40 before I drove to breakfast.

I believe it lost 30% the previous night. 102 went to 70 something.

I just picked up my car from the factory on Thursday 2-14-13, so I'm a little new to this. Does anyone else have this problem?

Blake

bfranks273 |
26. Februar 2013

Wow, dont have all the inter-day details , just went on a quick trip and left her outside unplugged in the DC area Fri morning to Tues morning . Roughly 45 to 25 degrees F daily. Ideal went 261 to 195 . It is worse than I saw in the fall so cold does have an add'l effect. V4.2.

Brian H |
26. Februar 2013

Probably, it's partly because the car doesn't know when you're going to want it again, and keeps the battery from dropping all the way to ambient outdoor temperature. When timing is available, you can let it drop all the way down; cold itself is not harmful, and will not reduce range. Charging and driving when cold is harmful, though, so allow enough time to pre-warm (preferably on "shore power") after a long "cold soak".

Brian H |
26. Februar 2013

Actually, after any length of "cold soak" it should be pre-warmed if possible. Starting out immediately when cold will cause the car to dump huge current into the battery heating system for a while.

AndresL |
07. März 2013

@Nick - Excellent post, thank you! I live in the same area and experienced the same issues these past 2 weeks with the temperature drops, losing as much as 14 miles a night (7 PM to 7 AM) when the temperatures reached the low 50s. I was also concerned and wondering about the losses, which definitely distort what Tesla promotes in terms of idle discharge rates, monetary savings and the general range of the car (when taking into account separate short trips over a period of weeks rather than a single long trip). I hope they come out with the next firmware version soon, and that it addresses the sleep mode and any other charge loss issues. I would certainly suggest to enable smart sleep modes, in which they allow most components to go into sleep mode but perhaps the vital ones necessary for a fast start-and-go to remain more "alert" for needs. Also a programmable timer on sleep mode would most probably take care of 90% of the problems, as most of us can easily predict 90% or more of our cars' idle times.

nickjhowe |
07. März 2013

At the Tesla Oslo event last night Elon said Tesla currently expects cars to lose 2-3% battery capacity each night (seems too optimistic based on our experience), and this will drop to 0.2% when they re-enable sleep mode.

Brian H |
07. März 2013

At the Oslo event, Elon said sleep would return before shipments to Europe began in July.

bobinfla |
08. März 2013

@Nick: Very excellent and timely post. I'll be parking my car for 7 1/2 days at Orlando Airport next week and this was exactly the real world data I came looking for today. Thanks.

Jolinar |
08. März 2013

@nickjhowe
If I read it correctly, your car lost 58 miles in 6.5 days. That means 8.9miles/day => battery would be empty (from full 265 to 0) in 29 days. That is parasitic load of 3.36% per day. More than Elon stated in Oslo (2-3%), but not that much more :-)

However I agree, sleep mode is needed.

nickjhowe |
08. März 2013

@Jolinar - I wonder how long that same drop would continue, and whether it would go down to zero. At some point the car goes into battery save mode. But I don't know when that would happen.

mw |
08. März 2013

98% of the time I plug my car in at night. On the few occasions I left it unplugged overnight, it lost about 10 miles of range in 30 F temps. I'm in Ohio. I have noticed on really cold days 12 F while parked at work I would get home with 150ish miles of range out of the 230 I had in the morning. That is a 42 mile round trip. 50% highway. So some was warming the battery after i started driving and some was loss while sitting. The android app wasn't released until after our cold snap so I wasn't able to pre warm the car. In the really cold temps my wh/mi were around 550 and in 45 F or greater I use about 300 to 350 wh/mi... depending on how heavy my foot is on the highway :) Usually drive 80. I have found that 45 F seems to be the tipping point for using more energy to warm the battery... at least that is when I notice the wh/mi going up.

dortor |
08. März 2013

Going to bed tonight with 250 miles range - will update status in morning - expect low 40s over night - first time over night

It looks like a lot of the confusion here is being created by using the "Rated Miles" number as the amount of energy left in the battery. This number is a computer generated number based on a number of things, mainly temperatures. We should instead be looking at the battery level. This is shown both on the dash, the app, and (most easy to read) the big 17" screen. If you watch that, you will see that during these cold soaks that cause the "Rated Range" to drop, the battery percentage has not moved my any more than expected due to the lack of sleep mode.

For example if you go to Nickjhowe great graphic, you can see that the battery percentages for each day are about: 74%, 72%, 68%, 65%, 62%, 59%, which fits with the range displayed also as the car was kept at about the same temperature the whole time.

Peter

DouglasR |
09. März 2013

@Peter7

Where do you see battery percentage on the dash, app, and touch screen? I must be missing it.

Peter7 |
10. März 2013

They unfortunately don't display the number on the screen, though you can snag it from the API if you mess with that stuff. But you can see the 10% marks on the battery displays, the rest is rough estimation. It's not perfect, but it does work.

Peter

prash.saka |
10. März 2013

For mine, the drop is closer to 1 mile per hour. I left mine in the garage at around 40 degrees for two nights and a day and the drop was over 30 miles, from 157 to 124.

Even now, when I left it outside where the temperature is over 40 degrees, the drop is 1 mile per hour, from 55 to 51 in 4 hours.

I can't charge it every night as the apartment complex isn't letting me use any power outlets. And I desperately need the sleep mode. Is there a way to rollback the software version, from 4.2 to 4.1, for just the sleep mode?

~ Prash.

DouglasR |
10. März 2013

@Peter -- I don't see 10% marks on the app. They might be on the displays; next time I get in the car I'll put my glasses on to look. I never noticed them before.

"I'm an engineer and am able to estimate range/conditions/etc (and enjoy it!), but to be really mainstream, I think Tesla can/should do more to help drivers manage their driving - they have not been really clear/open about parking- and temperature-related losses and the on-board tools and the app don't really help you estimate where you really stand. For example, they could integrate Nav, Weather and Energy apps and really give you a trip planner that takes a lot more into account. Right now, for example, I have to consider speed, route (climbs) and real-world consumption to plan a trip. For example, while you might have enough total energy to get home based on average consumption, if there is a big climb shortly before you get there you can still run out before the top! As more non-tech and non-early-adopter types buy, it will be too easy for them to mis-estimate and get stuck with the current tools."

Damian |
10. März 2013

There is one thing I am not clear about. I hear folks are charging in the cold and it seems as if they are not stopping at 80% but are allowing the battery to be charged all the way to 100%. I believe I saw recommendations to charge only to 80% since 100% will diminish the battery's capacity over the 8 year length of the battery pack. Has anyone else received this instruction?

Brian H |
11. März 2013

It seems to make a difference if you start driving right away. Sitting at 100% is the real problem.

ChristianG |
11. März 2013

@Damian,if I understood it right, they don't really charge up to 100% they put it on Range mode but don't allow it to lead fast, that way the battery pack will be heated when they leave shortly afterwards.

This is just a way to force the car to pre heat the pack. I don't know if that's still necessary with the app.

Peter7 |
01. April 2013

Hey BrianH,

Unfortunately it looks like the "Buddy Box" won't help. It still draws from a single 14-50, which is limited to 50A (40A continuous). My MI-EVSE needs two 50A supplies to merge to supply the 80A to the car.

Peter

RedShift |
01. April 2013

My car was at service last week. They charged to max range and let it sit in the lot.

When I asked about it, they said if you do max range once or twice a week it's fine.

I am not so sure though.

JayBoy |
02. April 2013

Peter,

Is your MI-EVSE being sold?

Jay

Divesh |
27. April 2013

I just started driving my Model S for the past 1 week. I travel everyweened from Yuma, AZ to San Diego, CA which is 185 miles. Yesterday was the first I drove this on Tesla. When I left Yuma I had 270 miles(standard mode charge) traveled at 67miles/hr(cruise cotnrol) when I reached San Deigo, was left with 28miles. Interior temp was 73 F.
I charged it in San Diego to 300 miles Max charge and parked in garage and within 8hours it has discharged to 265miles.
lost 35 miles in just under 8 hours.

Thom EM |
07. Januar 2014

@Damian: good eye on that engineering take. The basic problem is equating battery charge energy to "miles of range" when there are other demands on the energy, notably for environmental control, computer connectivity, hill climbing and the rest. My suggestion to Tesla:

* Allow us to put the main speedo display in energy units (as the switch advertises but doesn't deliver)

* Give us projected range (from the energy app) on the main speedo display of the energy app.

* Once that is done, follow the ideas below for integrating weather, Nav speed, topography, lodging and charger placements, with the energy app into an onboard trip planner like PlugShare, but better.

"I'm an engineer and am able to estimate range/conditions/etc (and enjoy it!), but to be really mainstream, I think Tesla can/should do more to help drivers manage their driving - they have not been really clear/open about parking- and temperature-related losses and the on-board tools and the app don't really help you estimate where you really stand. For example, they could integrate Nav, Weather and Energy apps and really give you a trip planner that takes a lot more into account. Right now, for example, I have to consider speed, route (climbs) and real-world consumption to plan a trip. For example, while you might have enough total energy to get home based on average consumption, if there is a big climb shortly before you get there you can still run out before the top! As more non-tech and non-early-adopter types buy, it will be too easy for them to mis-estimate and get stuck with the current tools."